Field of the Invention
The present invention relates to a technique for measuring a position and an orientation of an object by using a model indicating a shape of the object.
Description of the Related Art
Random bin-picking techniques have recently been developed to allow a hand mounted on a robot to grip one object among measurement target objects randomly stacked in a production line in a factory. Such techniques use a vision system to identify one object and measure a three-dimensional position and orientation of the object, so that the robot hand can grip the object. There is a method for calculating a position and an orientation of a measurement target object. According to the method, a recognition model for calculating the position and the orientation of the measurement target object is automatically generated using three-dimensional computer-aided design (CAD) data, to calculate the position and the orientation of the measurement target object. Then, the recognition model and measurement information acquired by distance measurement are subjected to fitting. According to this method, the vision system does not require to be customized for each measurement target object, and the vision system for each individual measurement target object can be provided by simply changing three-dimensional CAD data. Hence, this method is considered as effective.
Moreover, when the hand mounted on the robot grips an object, the presence of interference between a pallet and a measurement target object that may serve as a gripping candidate needs to be determined. Such interference determination is performed to check whether the measurement target object can be gripped before the measurement target object is determined as the gripping candidate. Even in such determination, geometric information of the measurement target object is necessary, and thus the three-dimensional CAD data is necessary.
A method discussed in Japanese Patent Application Laid-Open No. 5-127724 uses a contour edge line of a two-dimensional image to recognize a specific part within a measurement target object. In other words, the method discusses recognition of a portion instead of the measurement target object as a whole to calculate a position and an orientation of the measurement target object.